1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/compat.h>
3 #include <linux/errno.h>
4 #include <linux/sched.h>
5 #include <linux/sched/mm.h>
6 #include <linux/syscalls.h>
10 #include <linux/sem.h>
11 #include <linux/msg.h>
12 #include <linux/shm.h>
13 #include <linux/stat.h>
14 #include <linux/mman.h>
15 #include <linux/file.h>
16 #include <linux/utsname.h>
17 #include <linux/personality.h>
18 #include <linux/random.h>
19 #include <linux/uaccess.h>
20 #include <linux/elf.h>
26 * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
28 static unsigned long get_align_mask(void)
30 /* handle 32- and 64-bit case with a single conditional */
31 if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
34 if (!(current->flags & PF_RANDOMIZE))
41 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the
42 * va_align.bits, [12:upper_bit), are set to a random value instead of
43 * zeroing them. This random value is computed once per boot. This form
44 * of ASLR is known as "per-boot ASLR".
46 * To achieve this, the random value is added to the info.align_offset
47 * value before calling vm_unmapped_area() or ORed directly to the
50 static unsigned long get_align_bits(void)
52 return va_align.bits & get_align_mask();
55 unsigned long align_vdso_addr(unsigned long addr)
57 unsigned long align_mask = get_align_mask();
58 addr = (addr + align_mask) & ~align_mask;
59 return addr | get_align_bits();
62 static int __init control_va_addr_alignment(char *str)
64 /* guard against enabling this on other CPU families */
65 if (va_align.flags < 0)
71 if (!strcmp(str, "32"))
72 va_align.flags = ALIGN_VA_32;
73 else if (!strcmp(str, "64"))
74 va_align.flags = ALIGN_VA_64;
75 else if (!strcmp(str, "off"))
77 else if (!strcmp(str, "on"))
78 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
80 pr_warn("invalid option value: 'align_va_addr=%s'\n", str);
84 __setup("align_va_addr=", control_va_addr_alignment);
86 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
87 unsigned long, prot, unsigned long, flags,
88 unsigned long, fd, unsigned long, off)
95 error = ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
100 static void find_start_end(unsigned long addr, unsigned long flags,
101 unsigned long *begin, unsigned long *end)
103 if (!in_32bit_syscall() && (flags & MAP_32BIT)) {
104 /* This is usually used needed to map code in small
105 model, so it needs to be in the first 31bit. Limit
106 it to that. This means we need to move the
107 unmapped base down for this case. This can give
108 conflicts with the heap, but we assume that glibc
109 malloc knows how to fall back to mmap. Give it 1GB
110 of playground for now. -AK */
113 if (current->flags & PF_RANDOMIZE) {
114 *begin = randomize_page(*begin, 0x02000000);
119 *begin = get_mmap_base(1);
120 if (in_32bit_syscall())
121 *end = task_size_32bit();
123 *end = task_size_64bit(addr > DEFAULT_MAP_WINDOW);
127 arch_get_unmapped_area(struct file *filp, unsigned long addr,
128 unsigned long len, unsigned long pgoff, unsigned long flags)
130 struct mm_struct *mm = current->mm;
131 struct vm_area_struct *vma;
132 struct vm_unmapped_area_info info;
133 unsigned long begin, end;
135 if (flags & MAP_FIXED)
138 find_start_end(addr, flags, &begin, &end);
144 addr = PAGE_ALIGN(addr);
145 vma = find_vma(mm, addr);
146 if (end - len >= addr &&
147 (!vma || addr + len <= vm_start_gap(vma)))
153 info.low_limit = begin;
154 info.high_limit = end;
156 info.align_offset = pgoff << PAGE_SHIFT;
158 info.align_mask = get_align_mask();
159 info.align_offset += get_align_bits();
161 return vm_unmapped_area(&info);
165 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
166 const unsigned long len, const unsigned long pgoff,
167 const unsigned long flags)
169 struct vm_area_struct *vma;
170 struct mm_struct *mm = current->mm;
171 unsigned long addr = addr0;
172 struct vm_unmapped_area_info info;
174 /* requested length too big for entire address space */
178 /* No address checking. See comment at mmap_address_hint_valid() */
179 if (flags & MAP_FIXED)
182 /* for MAP_32BIT mappings we force the legacy mmap base */
183 if (!in_32bit_syscall() && (flags & MAP_32BIT))
186 /* requesting a specific address */
189 if (!mmap_address_hint_valid(addr, len))
190 goto get_unmapped_area;
192 vma = find_vma(mm, addr);
193 if (!vma || addr + len <= vm_start_gap(vma))
198 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
200 info.low_limit = PAGE_SIZE;
201 info.high_limit = get_mmap_base(0);
204 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
205 * in the full address space.
207 * !in_32bit_syscall() check to avoid high addresses for x32
208 * (and make it no op on native i386).
210 if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
211 info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
214 info.align_offset = pgoff << PAGE_SHIFT;
216 info.align_mask = get_align_mask();
217 info.align_offset += get_align_bits();
219 addr = vm_unmapped_area(&info);
220 if (!(addr & ~PAGE_MASK))
222 VM_BUG_ON(addr != -ENOMEM);
226 * A failed mmap() very likely causes application failure,
227 * so fall back to the bottom-up function here. This scenario
228 * can happen with large stack limits and large mmap()
231 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags);